Thousands of people rallied in the village of Sa'ar, west of Manama, responding to a call of the main opposition bloc al-Wefaq to protest against a crackdown on opposition activists.
The protesters were carrying pictures of jailed opposition leaders and banners containing messages for top international officials who are attending the two-day Manama Dialogue Forum opened on Friday evening.
"To those meeting at the Manama Dialogue (conference): Are you aware that there are female detainees in Bahraini jails?" read one banner.
"Why do you support democracy for people of other countries... (and not) in Bahrain?" read another banner.
Police attacked the protesters with tear gas and sound bombs trying to disperse them.
Similar protests were also held in the villages of Sanabis, Deraz, Sitra and Diya, where protesters burned tires and at some points clashed with security forces.
The protests come as British Foreign Secretary William Hague is planned to deliver the keynote address at the annual security forum upon its opening.
US Defense Secretary Chuck Hagel will also give a speech on Saturday, the second day of the forum which is organized by the International Institute for Strategic Studies.
According to the International Federation for Human Rights, a total of 80 people have been killed in Bahrain since the protests erupted in 2011.
Strategically located just across the Persian Gulf, Bahrain is home base to the US Navy's Fifth Fleet.
RA/MB